Backport PR #60206 on branch 2.3.x (STY: Fix lint error in test_where.py) (#60208)

Backport PR #60206: STY: Fix lint error in test_where.py

Co-authored-by: Matthew Roeschke <[email protected]>

Author: meeseeksmachine

pandas/tests/frame/indexing/test_where.py

@@ -4,8 +4,6 @@
 import numpy as np
 import pytest
 
-from pandas._config import using_string_dtype
-
 from pandas.core.dtypes.common import is_scalar
 
 import pandas as pd